The present invention relates to an operation apparatus for a vehicle automatic transmission mechanism, which apparatus comprises an actuator for driving a hydraulic valve for switching a travel range of the automatic transmission mechanism, a control means for controlling the actuator, and a transmission operation means for outputting a transmission switching command to the control means.
In general, an operation apparatus for a vehicle automatic transmission mechanism comprises a select lever as a transmission operation means, which is directly mechanically connected to a hydraulic valve for switching a travel range of the automatic transmission mechanism, and is moved by a hand of a driver. The driver moves this select lever to a desired travel range position to switch a valve position of the hydraulic valve, thereby selecting a desired travel range.
In a manual operation apparatus of this type, since the select lever and the hydraulic valve are directly mechanically connected via an arm, a link, and the like, a strong operation force is required to move the select lever. Therefore, demand has arisen for an operation apparatus which requires only a light operation force.
In order to meet this demand, in recent years, as described in, e.g., Japanese Patent Publication No. 63-37729, in a vehicle automatic transmission mechanism for controlling a hydraulic valve in a transmission by a wire coupled to the hydraulic valve to switch a travel range, a motorized range switching apparatus, which drives the wire using a driving motor, and operates this driving motor upon operation of an electrical switch, has been proposed. According to the motorized range switching apparatus, a driver need only operate the electrical switch to switch a travel range via the driving motor. Thus, the driver can operate the electrical switch with a light operation force to instruct to switch a travel range.
A conventional motorized range switching apparatus of this type, however, is controlled to cause a travel range position instructed by the electrical switch to precisely coincide with a travel range in the automatic transmission mechanism. For this reason, even when a malfunction or a system failed state wherein a control sequence runs away occurs in a control unit for making this control operation, a fail-safe mechanism capable of safely traveling a vehicle is required to reliably operate.